Camilla, Duchess of Cornwall has tested positive for Covid-19, Clarence House said on Monday, four days after her husband Prince Charles was revealed to have contracted the virus.

"Her Royal Highness The Duchess of Cornwall has tested positive for Covid-19 and is self-isolating. We continue to follow government guidelines," the statement says.

A royal source says the Duchess is triple vaccinated, and will continue to follow all government guidelines and review engagements on that basis.

Charles started isolating on February 10 after testing positive for the virus for the second time. The 73-year-old heir to the throne had to cancel his attendance at an event in the English city of Winchester on Thursday, according to a statement from his official Twitter account.

Charles is also fully vaccinated and first contracted Covid-19 in March 2020, as the global pandemic gripped countries around the world. He said at the time he was first infected that he had been lucky to only experience mild symptoms, adding he'd "got away with it quite lightly."

Charles had met with the Queen "recently," a royal source told CNN after his latest infection was announced. The source did not elaborate on how recently the meeting took place.

Last week, Queen Elizabeth II used her Platinum Jubilee to redefine the future of the monarchy as she called for the Duchess of Cornwall to be known as Queen Camilla when Charles eventually becomes King.

When Charles married Camilla in 2005, the couple announced she intended to be known as "Princess Consort" despite having a right to the title of Queen. It was seen as a recognition of the sensitivities around a title that was destined for Charles' first wife, Diana.